U.S. Pat. No. 4,105,776 to Ondetti et al discloses proline derivatives which are angiotensin converting enzyme (ACE) inhibitors and have the general formula ##STR1## which includes captopril ##STR2##
U.S. Pat. No. 4,168,267 to Petrillo discloses phosphinylalkanoyl prolines which have the formula ##STR3## wherein R.sub.1 is lower alkyl, phenyl or phenyl-lower alkyl;
R.sub.2 is hydrogen, phenyl-lower alkyl or a metal ion; PA1 R.sub.3 is hydrogen or lower alkyl; PA1 R.sub.4 is hydrogen, lower alkyl, phenyl-lower alkyl or a metal ion; and PA1 n is 0 or 1.
U.S. Pat. No. 4,337,201 to Petrillo discloses phosphinylalkanoyl substituted prolines having the formula ##STR4## or a salt thereof, which covers fosinopril ##STR5##
U.S. Pat. No. 4,432,971 to Karanewsky et al discloses phosphonamidate substituted amino or imino acids which are angiotensin converting enzyme inhibitors and salts thereof and have the formula ##STR6## which includes 1-[N-[hydroxy(4-phenylbutyl)-phosphinyl]-L-alanyl]-L-proline, dilithium salt ##STR7## and 1-[N.sup.2 -[hydroxy(4-phenylbutyl)phosphinyl]-L-lysyl]-L-proline, dilithium salt ##STR8##
U.S. Pat. No. 4,374,829 to Patchett et al discloses carboxylakyl dipepetide derivatives which are said to be angiotensin converting enzyme inhibitors and have the formula ##STR9## which covers enalapril ##STR10## that is, N-(1-ethoxycarbonyl-3-phenylpropyl)-L-alanyl-L-proline.
U.S. Pat. No. 4,452,790 to Karanewsky et al is directed to phsophonate substituted amino or imino acids and salts thereof having the formula ##STR11## which covers SQ29,852 ##STR12## that is, (S)-1-[6-amino-2[[-hydroxy(4-phenylbutyl)phosphinyl]oxy]-1-oxohexyl]-L-pro line.
U.S. Pat. No. 4,248,883 to Sawayame et al discloses 1-(3-mercapto-2-methylpropanoyl)prolyl amino acid derivatives of the formula ##STR13## wherein
R represents a hydrogen atom, a lower alkyl group, a phenylo-lower alkyI group or a substituted phenyl-lower alkyl group; R.sub.1 represents a hydrogen atom, R.sub.4 CO--, R.sub.5 S-- or ##STR14##
R.sub.2 represents a hydrogen atom or a lower alkyl group;
R.sub.3 represents a hydrogen atom, a phenyl group, a lower alkyl group, or a substituted lower alkyl group in which the substituent is hydroxy, phenyl-lower alkoxy, amino, guanidino, N-nitroguanidino, carboxyl, lower alkoxycarbonyl, phenyl-lower alkoxycarbonyl, carbamoyl, mercapto, lower alkylthio, phenyl, hydroxyphenyl, indolyl or imidazolyl; or R.sub.2 and R.sub.3 form a heterocyclic ring together with the nitrogen and carbon atoms to which they are respectively bonded; R.sub.4 represents a lower alkyl group, a lower alkoxy group, a phenyl group, a substituted phenyl group, a phenyl-lower alkyl group, a substituted phenyl-lower alkyl group, a phenyl-lower alkoxy group, a substituted phenyl-lower alkoxy group, a phenoxy group, or a substituted phenoxy group; R.sub.5 represents a lower alkyl group, a phenyl group, a substituted phenyl group, a phenyl-lower alkyl group, a substituted phenyl-lower alkyl group, ##STR15## or an amino(-carboxy)lower alkyl group; R.sub.6 represents a hydrogen atom or a lower alkyl group; R.sub.7 represents a lower alkyl group, a phenyl group or a substituted phenyl group; X represents an oxygen or sulfur atom; and the substituent in the substituted phenyl group is a halogen atom, a lower alkyl group, or a lower alkoxy group; and salts of said derivatives.
U.S. Pat. No. 4,316,906 to Ondetti et al discloseds ether and thioether mercaptoacyl prolines of the formula ##STR16## which includes zofenopril ##STR17##
Japanese Laid-Open Patent Application (kokai) No. 61-36217 discloses sustained-release ACE inhibitor formulations wherein the ACE inhibitor is suspended in a lipophilic (oil or fat) base together with one or more of ascorbic acid, sodium ascorbate, erythorbic, acid, sodium erythorbate, sodium hydrogen sulfite, sodium sulfite and metabisulfite, and a viscosity enhaner such as hydroxypropylmethyl cellulose or methyl cellulose. The lipophilic base is present in a weight ratio to the ACE inhibitor of from about 3:1 to about 12:1.
U.S. Pat. No. 3,365,365 to Butler et al discloses pharmaceutical compositions in the form of beadlets capable of being embodied in hard shell capsules. In one embodiment, beadlets contain and furnish two separate and distinct doses of medicament which is accomplished in part by an enteric coating containing zein and an abietic acid type resin. In a second embodiment, beadlets contain and permit an active medicament to be released in a continuous fashion which is accomplished by a series of layers including an adhesive gum acacia layer into which an active inhgredient is dispersed, and a permeable film of shellac and polyethylene glycol 4000 to 20,000 overlaying the medicament-coated layer.
European Patent Application No. 0122077 (Elan) discloses prolonged release theophylline multilayer granules or pellets formed of theophylline (3.59 g), organic acid, such as citric acid (875 g) and soluble polymer with an outer membrane of poorly soluble polymer.
European Pat. No. 123470A discloses sustained release propranolol which is formed of alternate layers of propranolol, organic acid and mainly water-soluble polymer with a less soluble outer membrane. Granules for oral administration include a nucleus of propranolol (1000 g) or its acceptable salt and an organic acid such as citric acid (500 g) embedded in a polymer material in a multiple layer arrangement with an external membrane.